Multivoice electronic organ



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United States Patent O 3,420,941 MULTIVOICE ELECTRONIC ORGAN Donald J. Leslie, Altadena, Calif., assignor, by mesne aS- signments, to Columbia Broadcasting System, Inc.

Continuation-impart of application Ser. No. 463,828,

June 14, 1965. This application Dec. 10, 1965, Ser.

No. 523,814 U.S. Cl. Sri-1.24 14 Claims Int. Cl. Gh 1/02 This is a continuation-in-part of application Ser. No. 463,828, filed June 14, 1965, now abandoned.

This invention relates to electronic organs.

In many electronic organs a plurality of voices are derived from a common set of generators. For example, to derive a flute tone, a complex generator is connected to the output via a flute lter or shaping circuit when the playing key operates a switch. This particular filter or shaping circuit is placed in circuit by operation of a typical stop or ta'b labelled appropriately. To derive a string tone, the very same complex generator is connected to the output, but through a different filter or shaping circuit operated by another stop or tab labelled, for eX- ample violin.

If the shaping circuits for flute and violin are operated separately, then Well-defined characteristic llute and violin tones are perceived, However, when they are operated simultaneously, flute and string tones are not separately perceived, but instead a new single tone results. This is far from the effect that might be achieved 'by operating two stops of a pipe organ since, in such circumstances, two different ranks of pipes would be operated. Such two ranks would -be heard in chorus for a number of reasons, including the fact that corresponding pipes Ifor C1 in the respective ranks cannot be in perfect tune.

The obvious remedy for such situation is to provide a number of sets of generators in the electronic organ. This has been done. In some instances, four sets are used for the four basic classes of tones-flute, string, reed and diapason, with each generator set in turn, through appropriate shaping circuits, providing a number of different tones. For example, the string generator can pro- 'vide the violin, cello and other related sounds. The difficulty with such an arrangement is that four sets of generators must be periodically tuned rather than one. Four sets of generators represent a multiplied initial cost and space requirement. And the various voices derived from the same generator still are not distinct.

In another type of organ, sine wave generators are used, and complex tones corresponding to different voices are built up by borrowing. Thus, for example, the second, third, fourth, fifth, and other harmonics for A4 are derived from the sine wave generators for A5, E6, A6, Cliq, etc. Usually, one bus bar is provided for corresponding harmonics of all of the notes. Thus a suitable scaling device operatively connected to the bus bar can proportion the strength of each harmonic relative to the fundamental whereby each note has the same voice characteristic. Since the same generators are used `for all the voices, again it is impossible to perceive separate voices.

The object of this invention is to provide an electronic organ system in which various voices may, in a simple manner, be made distinct without requiring additional generator sets. For this purpose, use is made of dynamic phase shift devices in each voice channel. Such dynamic phase shift devices produce variable phase shifts. If the variation in phase is uniform, a new constant pitch will be produced. If the variation in phase is non-uniform, the resulting pitch will be indeterminate. Due to the changing phase shift produced, a different pitch is created,

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whether determinate or indeterminate, and consequently the voices are separately perceived. Such dynamic phase shift devices are shown in my copending application, Ser. No. 350,717, filed Mar. l0, 1964, entitled, Electronic Organ System, now U.S. Patent No. 3,372,225.

The dynamic phase Shifters introduce the possibility of unmusical and annoying beat effects being created. To avoid this, each dynamic phase shifter feeds a separate output channel, which may comprise either separate speakers or other transducers, such as recording heads.

Another object of this invention is to provide a system of this character in which a single generator system can be used to provide a plurality of distinct voices for the organ. Thus where a set of generators is derived from twelve master oscillators, only twelve oscillators need be tuned.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of several embodiments of the invention. For this purpose, there are shown a few forms in the drawings accompanying and forming part of the present specification. These forms will now be described in detail, illustrating the general principles of the invention; but it is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawings:

FIGURE l is a single Wire diagram of an electronic organ system incorporating the present invention;

FIGS. 2, 3 and 4 are diagrams similar to FIG. l, each showing modified forms of the present invention;

FIGS. 5 and 5a together constitute a diagram showing still another modified form of the present invention: and

FIGS. 6 and 7 are diagrams illustrating alternate isolation circuits for use in the system shown in FIG. 5.

In FIG. 1, tone generators labelled C1, C111, D1, Dill, etc. are shown, representing all generators of a single set. These generators produce impulses corresponding to notes spanning a musical range of six or eight octaves. The lgenerators in this embodiment produce impulses rich in harmonic content. The generators all connect to a comrnon feeder circuit or bus connection through individually operable key switches 12, 14, 16, 18, etc. Three separate output circuits F, S, and R are driven Aby the connection 10. These output circuits respectively produce flute, string and reed type tones.

The output circuit F includes, in series, a stop or tab switch 20; a filter or shaping circuit 22 that -develops the characteristic flute tone in a well-understood manner; a dynamic phase shift network 24; a power amplifier 26; and an output transducer in the form of a speaker 28. The other output circuits S and R include similar components. Thus the string output circuit includes a stop or tab switch 3d, a shaping circuit 32, a dynamic phase shift network 34, an amplifier 36, and a speaker 38. The reed output circuit includes a stop or tab switch 40, a shaping circuit 42, a dynamic phase shift network 44, an amplifier 46, and a speaker 48. Of course, the three output circuits F, S, and R simply represent a plurality of such circuits; as many may be provided as desired.

The dynamic phase shift networks 24, 34 and 44 preferably are of the random type shown in FIGS. 6, 7 and 8 in my said copending application Ser. No. 350,717. Such dynamic phase shift networks produce frequency deviations that vary periodically, the deviations being in the range of one or two cycles per second flat or sharp. The sounds issuing from the respective speakers, assuming all the stop switches are closed, will have a definite identity due t-o the slight tuning variance. The voice characteristics added by the shaping circuits are retained, and

the listener clearly perceives the individual voices. Since separate speakers are provided for each voice channel, no beat effects are created by virtue of the phase shift networks.

In the form of the invention `illustrated in FIG. 2, two bus connection or feeder circuits 50 and 52 are provided for one set of generators. Generators corresponding to notes C, D, E, Ff, Git, and Ail are connected to the feeder circuit 50, whereas generators corresponding to notes Cit, Dit, F, G, A, and B are connected to the feeder circuit 52. One group of three voice circuits is driven by the feeder circuit 50 and another group of three identical voice circuits is driven by the feeder circuit S2. Each voice circuit includes elements corresponding to those described in connection with the voice circuits of FIG. l, namely, a stop or tab switch, a shaping circuit, a dynamic phase shifting network, an amplifier and a speaker. The six voice circuits are identifiable by reference characters 54, 56, and 58 for circuit 50, and 60, 62 and 64 for circuit 52. The voice circuits 54 and 60 include like shaping circuits; the v-oice circuits 56 and 62 include like shaping circuits; and the voice circuits 58 and 64 include like shaping circuits. These pairs of circuits are operated by the same stops or tabs 66, 68 and 70. Upon operation of the stop or tab 68, for instance, string tones are produced upon operation of the key switches.

Tones corresponding to C, D, E, Fit, Git, and Af are translated in one group of three output channels, whereas tones corresponding to other noted Cit, Dit, F, G, A and B are translated in the other group of three output channels. Thus, in accordance with my prior Patent No. 2,596,258, beat effects due to simultaneously sounding notes in either fourth or fifth interval musical relationship are avoided, as are beat effects due to mixing of out-of-tune voices.

The output channels 54 and 60, since they are coupled, 1.

may be regarded as parts of a single flute output channel. Similarly, channels 56 and 62 may be considered parts of a single string output channel, and channels 58 and 64 may be considered parts of a single reed `output channel.

The form of the invention illustrated in FIG. 3 is the same as in FIG. l, except that each generator has its own shaping circuits. Thus the generator C1 has flute, string and reed shaping circuits 72, 74 and 76 respectively that connect to three feeder circuits 78, 80 and 82. The generator CS1 likewise has flute, string and reed shaping circuits 84, 86, and 88 cooperable with the feeder circuits 78, 80 and 82, etc.

Each output circuit includes a stop or tab switch as at 83, a dynamic phase shift network 85, an amplifier 87 and a transducer or speaker 89. In this particular example, each shaping circuit is carefully -designed with respect to a particular fundamental frequency. A quite satisfactory arrangement is illustrated in FIG. 4. Also in FIG. 4, impulses corresponding to notes in alternate half tone relationship are translated in different channel groups. Thus the arragement in FIG. 4 bears similarity to the forms of both FIGS. 2 and 3. In this form, there are two groups of output channels 90 and 92 for alternate notes respectively. In this instance, simply by way of example, there are three individual channels for flute, string and reed. Thus, in one group 90, there are three speakers 94, 96, and 98. In circuit with the speaker 94, for example, are a stop or tab switch 100, a dynamic phase shift network 102, and an amplifier 104. Corresponding elements are present in the other output channels.

The output channels are fed by six feeder leads 106, 108, 110, 112, 114, and 116. Flute, string and reed shaping circuit 118, 120, and 122 connect with three generators C1, D1, and E1 through key switches 124, 126, and 128. These shaping circuits respectively connect to the feeder leads 106, 108, and 110 for one group of output channels. Flute, string and reed shaping circuits 130, 132, and 134 connect with three alternate generators C111, D111, and F1 through key switches 136, 138, and 140. These shaping circuits connect to the feeder leads 112, 114, and 116 for the second group of output channels.

In a similar manner, shaping circuits 142, 144, and 146 connect generators F111, G11, and A11 to the feeder circuits 106, 108, and 110. Shaping circuits 148, 150, and 152 connect alternate generators G1, A1, and B1 to the feeder circuits 112 114 and 116. For each octave set of twelve generators, there are four groups of shaping circuits, one group for C, D, and E; another group for Ff, Git, and All; another for Cit, Dit, and F; and another for G, A, and B. In this manner, each shaping circuit can be specifically designed for a narrow band of fundamental frequencies, and, at the same time, beat effects due to fourth and fifth interval notes are avoided.

The systems as thus far described may be embodied in a wide variety of organ systems. For example, there may be three sets of generators, with one or more of the sets provided with a plurality of output channels in which dynamic phase shift networks are incorporated. The shaping circuits may be designed for individual notes, or for any group of adjacent notes. There may be as many ndividual shaping circuits in a set as desired.

`In the form of the invention illustrated in lFIGS. 5 and 5a, the generators A4, A14, B4, etc. all produce substantially sinusoidal signals, that is, impulses free of harmonics. The generators may be of any known type. One generator is provided for each note, the signal produced corresponding to the fundamental of the note. Thus, the signal produced by the generator A1 has a frequency of 440 cycles per second.

In order to derive a complex wave form corresponding to a desire voice, a borrowing system is provided. For this purpose, each key has associated therewith, a series of switches. Thus, the key for A4 has switch arms S1, S2,

l S3, S4, S5, S6, and S2 that respectively are engageable with output bus bars B1, B2, B3, B4, B5, B6 and B2. These bus bars are designed respectively to transmit to the output system, impulses corresponding to the fundamental, the second, third, fourth, fifth, sixth and eighth harmonics. Thus the bus bar B., conducts the fourth harmonic of A4 when the key corresponding to A1 is depressed. The switoh S4 connects, via an isolation resistor 162 and a lead 164 to the generator A6. The generator A6 produces a signal of 1720 cycles per second. This corresponds not only to the fundamental of A6 but also to the fourth harmonic of A4. Hence, the signal of A6 is borrowed and used as the fourth harmonic of A1, all in a well known manner.

The bus bar B4 also transmits the fourth harmonic of C4. Thus, the key 166 for C4 operates a series of switch arms T1, T2, T2, T4, T5, T6, and T11 that also respectively engage the bus bars B1, B2, etc. The switch arrn T1 connects, via isolation resistor 168 and lead 170 to the generator G6 which produces a signal that corresponds to the fourth harmonic of C4.

Only a few of the connections for the entire organ are shown for two keys, but from the foregoing description the nature of the entire instrument will be understood. WheneNer any key is depressed, the fundamental and all harmonics exist in full strength respectively at the bus bars B1, B2, B3, etc.

A number of diiferent voices may be derived from the bus bars B1, B2, B3, etc., lfor application to separate output channels O1, O2, O3, etc. (FIG. 5a). Each output channel includes a stop switch W1, W2, W3, etc. interposed in the corresponding electrical output leads L1, L2, L2, etc. The leads L1, L2, L3, etc. respectively drive transducers or speakers 172, 174, 176, etc. through dynamic phase shift networks 178, 180, 182, etc. As in the previous forms, these phase shift networks are preferably of the random type, and produce frequency deviations averaging about one or two cycles per second. By virtue of the phase shift networks, the voices issuing from the speakers of the channels may be separately perceived.

In order to provide a selected harmonic content for impulses applied to the electrical output lead L1, a rst set of potentiometer resistors 184, 186, 188, 190, 192, etc. is provided that connect between ground and the respective bus bars B1, B2, B3, B4, etc.

Cooperable with the potentiometer resistors are sliders 194, 196, 198, 200, 202, etc. that tap off a selected portion of the signals corresponding to fundamental, second, third and other harmonics. These sliders all connect to the electrical output lead L1 through isolation networks 204, 206, 208, 210, 212, etc. These isolation networks prevent the signal across any one of the potentiometer resistors from being drained off through the other potentiometer resistors.

The sliders 194, 196, 198, 200, 202, etc. can be adjusted for desired strength Iof harmonics thus to synthesize any desired voice. A second set of potentiometer resistors 214, 216, 218, 220 etc. is provided that 'cooperate with the electrical output L2 and the channel O2 for synthesizing a different voice.1As many additional sets of potentiometer resistors and related circuit components may be provided as there are output channels. In this instance, only three output channels have been shown, but as many may be provided as desired. The sliders for the potentiometer resistors may be externally. accessible for adjustment by the organist, or they may be preset with only the stop switches W1, W2, W3, etc. accessible; optionally, some may be accessible and others not. In any case, by virtue of the isolation networks, a number of voices may be simultaneously operative without danger of sho1t circuits or excessive robbing of signals.

Typical isolation networks are illustrated in FIGS. 6 and 7. tIn FIG. 6, a transistor amplifier 222 is illustrated with its base connected to the tap 194. The transistor has its own bias resistor 224. The electrical output lead L1 connects to the collector of the transistor. Similarly, transistor amplifiers are provided for the other potentiometers. A common load resistor connects the collectors to a suitable source. A common D.C. blocking condenser 228 is interposed in the lead L1. The transistors provide the requisite high input impedance for isolation purposes wlhile the output impedance is sutiiciently low for coupling purposes.

In 1FIG. 7, a simple resistive network is provided. A relatively high resistance as at 230 is interposed between each slider as at 194, and the output lead L1. A common low impedance terminating resistance 232 is provided for all of the signals from the set.

In practice, one of the phase shift networks or devices 24 in FIG. 1 can be deleted Without sacrifice in function since the other networks produce the requiste relative shift. Similarly one of the networks 178, 180 or 182 in FIG. a may be deleted. In FIGS. 2 and 4, one de'vice in each group can be deleted without change in function. To ensure appropriate separate identities, the phase shift devices are, of course, asynchronous with respect to each other.

The inventor claims:

1. In an electronic organ: a set of tone generators; a plurality of shaping circuits in circuit with said tone generators for producing a variety of voices; a plurality of separate output channels for the respective voices, each including its own transducer means, substantially all of said output channels including dynamic Phase shift means whereby the said voices acquire separate identities as they are translated by said transducer.

2. The combination as set forth in claim 1 in which each output channel includes a stop or tab switch for optionally conditioning the output channel for operation.

3. The combination as set forth in claim 1 in which said dynamic phase shift means produce an indeterminate frequency characteristic within a limited range.

4. The combination as set forth in claim 1 in which each output channel includes companion parts for impulses corresponding to notes in alternate half tone relationship.

5. The combination as set forth in claim 1 in which groups of tone generators are provided with their individual shaping circuits.

6. The combination as set forth in claim 1 in which each output channel includes companion parts for impulses corresponding to notes in alternate half tone relationship; and in which groups of tone generators are provided with their individual shaping circuits.

7. The combination as set forth in claim 1 in which the voice shaping means consistsof circuits that mix a plurality of sine waves in harmonic relation in various strengths.

8. In an electronic organ: two groups of output circuits, at least ea-ch output circuit except one in each group including a dynamic phase shift device; each output circuit including a transducer and a stop switch; a set of generators for notes in a musical range; key switches for the generat-ors; a plurality of .circuit means connecting each generator in alternate half tone relationship to output circuits of one group; circuit means connecting each generator in the other alternate half tone relationship to the output circuits of the other group; and shaping circuits in each of said circuit means.

9. The combination as set forth in claim 8 in which said circuit means branch to provide separate circuits for limited groups of generators, each branch having its said shaping circuits common to the generators of the group.

10. In an electronic organ: a set of tone generators; a plurality of separate output channels each including a transducer; circuit means deriving from the generators, a plurality of distinct voices, and connected to said output channels; substantially all of said output channels including dynamic phase shift means whereby said voices acquire separate identities as they are translated by said transducers.

11. The combination as set forth in claim 10 in which each of said output channels includes its own shaping circuit for imparting the characteristic voice to the corresponding channel.

12. The combination as set forth in claim 10 together with: a set of playing keys corresponding to notes in a musical range; the generators of said set producing substantially sinusoidal impulses corresponding to said notes; a set of bus bars for translating harmonic components; a set of key switches for each of said keys and cooperable with said bus bars respectively; connections between the key switches and the generators for applying to said bus bars signals corresponding to the harmonic components of the key; a set of potentiometer resistors for each of said output channels, and connected respectively to the bus bars for lderiving signals therefrom; sliders for each of the potentiometer resistors; and individual isolation networks connecting each slider to the corresponding output channel.

13. The combination as set forth in claim 12 in which said isolation networks comprise transistor amplifiers having a high input impedance and a low output impedance.

14. The combination as set forth in claim 12 in which said isolation networks comprise high impedance elements.

No references cited.

ARTHUR GAUSS, Primary Examiner.

DONALD D. FORRER, Assistant Examiner.

U.S. Cl. X.Rv 

1. IN AN ELECTRONIC ORGAN: A SET OF TONE GENERATORS; A PLURALITY OF SHAPING CIRCUITS IN CIRCUIT WITH SAID TONE GENERATORS FOR PRODUCING A VARIETY OF VOICES; A PLURALITY OF SEPARATE OUTPUT CHANNELS FOR THE RESPECTIVE VOICES, EACH INCLUDING ITS OWN TRANSDUCER MEANS, SUBSTANTIALLY ALL OF SAID OUTPUT CHANNELS INCLUDING DYNAMIC PHASE SHIFT MEANS 